Simplify the following expression: $k = \dfrac{a}{8} - \dfrac{a}{3}$
Answer: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $8$ and $3$ $\lcm(8, 3) = 24$ $ k = \dfrac{3}{3} \cdot \dfrac{a}{8} - \dfrac{8}{8} \cdot \dfrac{a}{3} $ $k = \dfrac{3a}{24} - \dfrac{8a}{24}$ $k = \dfrac{3a -8a}{24}$ $k = \dfrac{-5a}{24}$